The present invention relates to a process for cracking metal-containing feeds in the presence of a fluid cracking catalyst composition comprising a zeolitic crystalline aluminosilicate, sepiolite and a matrix material. A catalyst composition of the type indicated above is disclosed in U.S. Pat. No. 4,266,672, wherein it is stated that the presence of the sepiolite permits obtaining a catalyst which not only provides excellent cracking, but also outstandingly good demetallization, particularly of heavy feeds such as petroleum residua.
Sepiolite is a mineral which is often in the form of rods of lath-shaped or fibrous, hydrated magnesium silicate (Mg.sub.2 Si.sub.3 O.sub.8 2H.sub.2 O). A description of sepiolite is found in the books Clay Mineralogy, R. E. Grim, McGraw-Hill (2nd Ed 1968), and The Electron-Optical Investigation of Clays, J. A. Gard, Ed., published by Mineralogical Society (1971). The sepiolite usually occurs in the form of bundles of generally parallelly oriented rods. In the above-mentioned patent it is stated that in order to make the sepiolite suitable for use in the cracking catalyst, the mineral must be broken up so that the sepiolite rods are disconnected. Each sepiolite rod should therefore be freely movable with respect to other rods. Dispersal or fibrillation of the rods can be accomplished by intensive grinding, kneading and the like. These treatments are, of course, time consuming and costly.